This invention relates to multi-channel array droplet deposition apparatus and to a method of manufacture thereof.
In U.S. Pat. Nos. 4,887,100; 4,992,808; 5,003,679; and 5,028,936 there is disclosed multi-channel array droplet deposition apparatus, suitably, for use as drop-on-demand ink jet printheads and of the form comprising an array of parallel channels mutually spaced transversely to the channels in the array direction. These printheads employ piezoelectric actuators forming at least part of the channel separating side walls as the means for effecting droplet expulsion from nozzles communicating respectively with the channels. One preferred method of making such a printhead comprises providing a base sheet having a layer of piezoelectric material poled normal thereto, forming a multiplicity of parallel grooves in the layer of piezoelectric material so that the material affords channel separating walls between adjacent grooves, the ink channels thus being provided by the grooves, forming electrodes on the channel facing surfaces of the walls so that the actuating electric fields are applied normal to the direction of poling in the array direction to produce deflection of the walls in the direction of the applied fields, connecting electrical drive circuits to the electrodes, bonding a top sheet to the walls to close the ink channels, providing nozzles for the respective channels and further providing ink supply means communicating with the channels.
In one design, the channels separating walls comprise piezoelectric, so-called, “chevron” actuators in which upper and lower parts of the walls are oppositely poled so as to deflect into chevron form transversely to the corresponding channels. One method of forming the base sheet from which the channels and channel separating wall actuators are formed consists of using a five layer laminate as disclosed in PCT International Publication No. WO 92/09436. In an alternative design, there are employed, so-called, “cantilever” actuators which are disclosed in U.S. Pat. No. 5,016,028. In U.S. patent application Ser. No. 08/480,541 filed Jun. 7, 1995 and counterpart PCT International Publication No. WO 91/17051 there is disclosed an array of parallel ink channels formed from a number of like modules each having a multiplicity of parallel ink channels, the modules being serially butted together. In a preferred form pairs of the butted modules form an ink channel at the butting location.